Carburetor



May 28, 1935.

J. S. CULP CARBURETOR 3 Sheets-Sheet 1 Filed July 30, 1932 INVENTOR @fol/UM ATTORNEYS.

May 28, 1935. J. S. CULP V CARBURETOR Filed July 3o, 19:52

3 Sheets-Sheet 2 INVENTOR day 5. Caf/Z7 62,50%/ @hay ATTORNEYS.

May 278, 1935. J, s CULP 2,002,732

CARBURETOR Filed July 50, 1952 5 Sheets-Sheet 5 s A Q, l Qt( il lq g i g Q, g l

i 'f [I] Fl l l w y r v w k 't l R i. l l@ f lvENToR Jay 5. Calf.

ATTORNEYS Patented May 28, 1935 .l' S.. Culp, Detroit', liIich., issi'gnol to Monarch Governor Company, Detroit', Mich., .a corpora'- Ation of Michigan pplication July 305 1932,. Serial No. 626g638i 15 Claims.

: This invention relatesito carburetors. forY inter` nal combustion: engines; anobiect ofthe invens.- tion-being. toV provide an improved device of. this characterl which will be moreY efficient and effective in operation; relatively simple in .construction. therefore, more economical to manufacture; and' which. will be more; adaptable to-various4 of engineswhile permitting. better control or'lgfoverning of thefuel mixture in accordance. with enginerequirements.

A. further object of. the invention: is to provide a carburetor or fuel. mixture governing device Whichithe thrcttlevalvermevement is controlled result ot variationsfin; pressure in the intake passage.; and wherein the fuel is. metered. in an improved' mami' so.` as to effect a fuel supply. varying' in accordance withuthe engine requirements.. f i i T A iurther object is; to. provide a suction responsive throttle: valve adapted to control.i the inflow of fuel into the mixing chamber or,.more specifif cal1y,. adapted. to;v control by its movement afmeltering; meansgfor the fuel, yet.,` in which. the fuel'. sumzaiyA iscontrolled' at different. speeds independ-V ently of the,- engirie suction or throttle Valve.

movement. Y

Another object of' the. invention isA to. provide a.. carburetor .or fuel. mixture governor having a; streamlined.` throttlevalve Working. in cooperationf Witlfr a: venturi. in the intake; also to.-` provide` a;l

throttlefvalveworking in cooperationwitha fuel whereby at idling speed when the throttle is the enginesuction' will: open a fuel'. and; aiu cnnduiti past. tile-throttle; .and inwhiclr the fuel nozzle will bef closed. when the engine is not.' opera-tingf..

A2 iurther object ci the invention is.- to: provide: a carburetor preferably of. the down. draft kind, having a suction actuated throttle. valve. located; preferably' inaventuri passageA and carrying. a. variable speed metering pin` cooperating-j withfaA fuel nozzle, and inl which the metering pinchas` a movement corresponding to the throttle valve movement andal'so has at predetermined times a movementindependently'thereof. 4Another ob'- ject is to'` provide improved means Wherebyvthe fuel nozzle' maybe adjusted relative to. the metering, pin. to. enrich the mixture, and in which the A.

position of the throttle valve itself may be ad'- J'usted'. f .Y y

i Other .objectsof this `invention will appear in. the. iollowing description andA appended. claims,. reference being had; tothe accompanying drawingsformingqa part of thisrspecication where?.

in likev reference characters designate corresponding partsI in the several views.`

Fig. 11 is a vertical section illustrating one forma of device embodying, the invention.A

Fig. 2 is a rightfhomdfsideelevation ci the struc- 5` ture of Fig. 1f,4 the'hood being shown in section'.

Fig.. 3 is a fragmentaryl left hand sideelevationoi the structure of: Fig. 1', the.r hood being in section.

Fig. 4 is` in part. an enlarged section through linesA--llf of Fig. l. Y

Fig. M5.- is a; vertical section illustrating another formy oi device embodying. the invention.

6is arightlhandV side elevation of thestructure of Fig. 5, the hood being in section'.

Fig. `'7 is a section: through; lines. 'lg-f-l of: Fig. 5.

Fig-t 8- is! an enlargedvew of` the metering pin.

Fig. 9 illustrates graphically a: power curve pro-- ,ducedA in thef use ot themetering constructed-f substantially' accordance with Eig. 8^.

Before explaining in detail7 the present. inveni tion it-is tobe understood that theinventionY is' not limited in. its application to the details of construction andv arrangement of parts illus'- trated in the' accompanying drawings since the invention is capable. of other embodiments and of. beingv practicada. or carried out in. various ways. Also it is to be understood that the phrase'ology' or terminology employed. herein; is for the pur'- pose of description andr not of limitation, and it' is. not intended-.to limittheinvention claimed here`- inA beyond` the requirements ofi the prior. art..

Referring to1 l: toA 41 inclusive the carburetor is provided with a. tubular conduit member Hl adaptedto be bol-tedLto.- intake portion H: of the engine manifold; and provided inl` its length: with. a Venturi portiom l 2 having: its: max-- imum constriction atA |13.; The.` tube t0 forms aguide: for a. slidable sleeve Mg. and adjacent theupper end of thedeVice-theparts to and 'My are cut away at` opposite sides: at. l5v to provide air passages.` Mounted: on-.thefupper endfof the sleeve I4. and centeredby am extension:` t6 of the sleeve? isa hood or canopy I-TL. the parts being. clamped: together by a knurled nutt l@ threadedv onto? the' portion l-Bz The hood'- I'T not only provides? am` enclosure for the device but also acts as? an air cleaner since the air enters at the lower open en'dof the hoo'dg. travels: upwardly,l thenl passes* at right. anglesthrough the apertures |-5 and thence down-- Wardly. A return: bent air streamis produced;` The relatively lower velocity ot the air. entering the lower ende of the hood: as; compared? with the higflrl VeIOcityot the' air: after theair stream` lsf bent, permits heavier than air dirt particles tol gravitate out of the air stream before entering the mixing chamber.

The sleeve |11 in the present instance has a downwardly extending tubular portion is tapped at its lower end to receive the screw threaded stem 28 of a fuel nozzle 2l. The stem has a longitudinal bore leading to a metering passage 2| a cooperating with the metering pin, later described, and thence terminating in an enlarged orifice 2lb. The fuel preferably enters the tube i9 through a passage in a plug 22 which has an exteriorly tapered portion over which extends the expanded end of a exible fuel pipe 23, the parts being clamped by a nut 24, as illustrated in Fig. 4.

Mounted within the Venturi portion I2 of the tube Hl is a throttle valve 25 which, in the present preferred embodiment of the invention, is in the form of a plunger. The head of this plunger is annular and is adapted to t into thev neck or constriction i3 vof the venturi so as to close the passage,'in the manner illustrated in Figure 1. The throttle valve or plunger 25 is provided Vwith radially extending guide wings 25 slidingly engaging vthe wall of the tube l, thereoy centering the valve in the passage throughout its movement between open and closed positions. It will be noted that the headY of the plunger which receives the impact of the inflowing air is tapered od from its center point beneath the fuel orice 2 lb. Moreover, the plunger is streamlined, the sidesthereof tapering inwardly at substantially the same anglefas the reverse taper of the venturi.

Cooperating with the fuel nozzle 2i is a metering pin 21, see Figs. l and 8, this pin together with the fuel orifice providing means for metering the charge of fuel to the engine. In the present instance this metering pin is carried by the throttle valve 25, and has a cylindrical portion 21a. extending freely through a central opening or duct 28 in the head of the plunger 25. This opening is undercut to receive the head 21h of the pin. It will be seen that a fuel passage is provided past the portion 21a of the-metering pin and this communicates with-a duct 29 leading into the intake passage, thereby permitting suicient air and fuel to flow throughthe throttle valve, when closed, in-order to idle the engine. The metering pin also-is formed with a tapered valve portion 21o below the fuel orifice-or inlet 2lb,which valve portion is effective Vto close off the inlet upon elevating the metering pin when the throttle valve is in its closed position.

The metering pin is supportedY on the upper end of a' piston 3S movable within a piston chamber 3l in the -plunger 25.' The piston is chambered to receive a light compression spring 32 held in place by a`plug member 33 pinned at 34 to the end of the plunger. The piston chamber at its lower end communicates with the intake passage through a port .t5-in the member 33. Hence the piston 3G at one side is subject to atmospheric pressure and at its opposite side is subject to the pressure prevailing at the engine side of the throttle valve,l which in the present instance is the static pressure in the intakeV manifold.

The member 33 has a socket to receive a ball 3S` spring 49.

plunger or piston has a reduced portion adapted to slide within a cylinder 44 pinned at 45 to a bracket 45 extending from the sleeve I4. The piston 43 is open to atmosphere at its lower end and on its upper end there is seated a vacuum valve 41 provided with a depending guide stem 48 extending into the bore of the piston. Surrounding the piston and confined between anges on the piston and the cylinder 44 is a relatively light compression spring 49. The construction provides an air dash pot, so that the upward movement of the piston 43 is resisted by th-e compression of air in the closed pocket above the piston. This movement also compresses the The piston will move freely in the opposite -direction under the influence of the spring 49 since the valve 41 will lift from its seat -equalizing the pressure at opposite sides thereof.

The varying positions of the throttle valve 25 are controlled by means of a throttle lever 50 pivoted at its upper end at 5I to the conduit or casing I il. Connected to the lower end of the lever 5@ is a rod 52 through the medium of which the lever may be manually operated by means of the usual foot pedal on the floor of the car, -or in any oth-er suitable manner. Intermediate its ends the lever has a projecting stud 53 overlying the end l0 of the lever 31. The latter may be adjusted as to its lower limit of movement by means of an adjusting screw 54 extending through a tapped hole in a bracket 55.

In the present instance a manually controlled adjustment of the metering means is provided so as to vary the fuel flow at the nozzle orifice, particularly where it is desirable to enrich the mixture upon starting the engine. The casing l0 has a boss 56 in a vertical bore of which is located an adjusting screw 51. The latter is adjusted vertically by means of a knurled nut 58. The upper end of the screw engages a projecting lug 59 on the sleeve I4. Thus by turning the nut 58 the sleeve and hence the nozzle 2l may be raised or lowered so as to adjust the relative positions of the nozzle and metering pin. Pivoted to the shank of the screw 51 by a pin 6l] is a cam lever 6i having a cam portion Gla adapted to rest against the under surface of the lug 59. A rod or link 62 is connecte-d to the lever and may be manually operated from the dash or steering wheel to raise the sleeve i4 as indicated in dotted lines in Fig. 3 so as to adjust the fuel nozzle relative to the metering pin. This adjustment by means of cam lever 6l is resisted by a return spring 63 surrounding a stem 64 constituting an extension of the screw 51. The lug 59 slides freely on the stem and the spring 63 is conned between this lug and an adjusting nut 65 on the end of the stem.

Referring particularly to Figures 8 and 9, the metering pin in the present instance is constructed so as to vary the fuel flow through the metering passage 2 la., and hence through the fuel orifice 2lb, in accordance with engine requirementsand this construction is such as to produce any -desired power curve. For the purposes of illustration, in the present instance the metering pin has successive sections of differ- Yent construction to produce substantially the power curve plotted in Fig. 9, comprising a tapered portion 21d for progressively increasing the fuel charge up to approximately thirty miles per hour, a straight section 21e of uniform diameter for maintaining a constant fuel flow up to approximately fty miles per hour, and a tapered acarrea section 2U' for increasing the fuel. charge;'at.

higher Speeds. Sect-ion 2H of the metering provides the required enriching the-mix;- -ture at, the. higher ranges on account` of the wind dragon resistance which varies in'proportion. to the etf'ectivearea-j of the vehicleand: the square of the velocity. construction of the metering will, cf course, vary in accordance with the engine requirements. and; may be determined byV the. power curve obtained by dynamometerntests. HenceV the metering device can bel designed for any desired power curve. i l i- Referring to Figures: 5. to. 'T inclusive, the embodiment therein illustrated issubstantially the` sameinv construction as that abolve'described except forY slight variations in design and the following features. The. lever end 411i is pivoted on a pin 4l between the forked extensions 66; of a member 6J threaded into theil'ower: end ofl a thimbleA 68,` havfmg-.a stem4 69. extendingfreely throughav hole in a lug lllf extending from the sleeve |24; This lugI forms.' a thimbleto confine position of said throttle valve. therefore, theengine cannot be flooded by any one end of a spring 1,2', the opposite end ofwhich is4 confined by the thimble 68'.. VBy turning the slottedv head 'M the member may be adjusted relative to the member4 61, thereby raising the sleeve I4 and the nozzle 211. A

An arm 13 hass an offset portion at oneend which is connected with the; end: 40, of' the lever 3T. The other end ofthe arm is provided with an offset portion 'la which projects ,throughV a slot 'M'formed in a footI throttle-'operated lever 15'. The lever 151 is pivotallyI mounted upon a fixed shaft orsupport 10 carried by the conduit I0., and is connected with the usual accelerator pedal by a rod or l-inkl'l. A leverilfiis also pivotally mounted upon the shaft 16 and is connected by alrod@ or link 19 with the usual hand throttle (not shown). Referring to Figure 6, when the accelerator pedal is depressed, the-lever 't5 is moved from its full line position to itsl dotted line position, thereby releasingv the throttle valve 2-5 to permit it to be actuated by enginesuction. On'the othery hand, however, when the hand? throttle isactuated, thelever- 18- is rshiftedand by reason of the lever engaging the ofsetlof, thearmfw is moved, and" (Fig. 2) or 15 (Fig. 6), when moved- 'toward the right, close the throttleA valve, itis to be noted that whenthey are; moved inthe' opposite direction they donot move the throttle valve, but simply release the valve vso that it i's free to be i opened by engine suction. Even though the foot pedali (accelerator) were suddenly depressed toa full open position, the onlyfunctionfof the levers 50 orn l5'v is to release the throttle valve. Such movement of the foot pedal' does-not affect the For this reason,

action ofthe levers 50- or 1-5, it being understood that the throttle valve opens only progressively astheengine suctionincreases. i

In Eiguref, IrhaveshovvnVL means for adjusting the relative fixedA positions of-- the nozzle 2|and the metering pin 21.. In the present embodiment,

the conduit lillF is provided with an. offset well or socket portion 8l);` andi theslidable sleeve l4-with a U2.- whiclr projects into the socket andfhas a loose sliding fit. therein, A screw 8.3` extends,

through a hole in the lug and is threaded into the.

base of the socket. A compression spring 8l, located within the.- socket, surrounds the shank ofthe screw and its ends engage the lug and the. socket. When an adiiustment. is desirable, this can be` effected by adjusting the screw 831 to raise the nozzle relative'to. the metering pin.

. It will be noted thatthe throttle valve or plunger .is preferablyv integrally chambered to receive a piston which` is actuated by a light spring. lThis piston' bears against'` the lowerend or head of the metering pin which head is located in a counter bore in the valve andcontrolsaport through the valve for the fuel. At idling speed there is a considerable depression at the .lower side ofV the throttle ii. e. the pressure is much less at the engine` side than at the atmosplfieric side.

Hence, the pist-on will bev Withdrawn andwill' open:

the fuel port. On the other-'hand at high speed" where thepressure tends to equalize at opposite sides of the throttle valve, which is open atl this. time, the spring is sufficientlyl strong to move the piston upwardly and close the fuel portin the throttle valve, thereby moving the metering pin and effecting a leaning out of the mixture which Iis, desirable at high speeds. When the throttle valve is closed' and' the engine stoppedA the spring 32- will= move the metering pin so as to cause its ualve to. close the fuel orice 2 Ib.

It will also. be noted, among other features,

that thepresent invention provides af carburetor having a throttle valve adapted tobe opened solely by differences in pressures. in. theintake pas# sage,;and also a single fuel nozzle and metering device for metering the fuel flowing through the nozzle, and inwhichlthe movement ofthe throttle to control the effective area of the intake passage adjacent the throttle is proportionate to the variationA in engine suction whereas the control of the fuel flow by themetering means isinde-v pendent ofthefengine suction andv may be predetermined toproduce any desired power curve.

In the present illustration of the invention I have preferred to combine the various novel fea-v tures in connection with a down draft carburetor in which the fuel is delivered to the fuel nozzle by means of a fuel pump operated from the engine. An improved fuel feed to the nozzle orifice is produced by virtue" of the present utilization of a fuel pump and a downwardly directed fuelnozzle, and a positive fuel charge is always ensured on account of the head of fuel formed under pressureabove the fuel pipe inlet in a closed air pocket.

It will be understood that the invention is not limited tov the foregoing type of carburetor nor to an arrangement requiringthe use of a fuel pump. Moreover, althoughit is preferred to employ a-vacuum operated throttle valve in the form of a stream lined plunger, the invention is not restricted to this construction, as a butteriiyvalve ofthe balanced or unbalanced kind might be utilized. Although the valve is described as opening under engine suction, it is understood that this includes any diiferences in pressures'eiective in theintake to influence the-valveand resulting either from the engine operation' directly or, iii-- directly, as for examplethe impact action of the mixture on the throttle valve due toithekinetic` energy' of the air or air and fuel mixture,-4 orpressureeifccts resulting from theuse of a superl-v charger.v It is understood that in describing the throttle valve as actuated by engine suction or vacuum or` theilike it is intended comprehend within such description a partly or Wholly supercharged engine.

I claim:

1. A carburetor having a lmixture psage, a fuel conduit, an idling speed valve adapted to close the fuel conduit, a main valve adapted to close the mixture passage and located at the engine side of said conduit, both of said valves being independently opened and as a result of suction effects induced by operation of theengine, and fuel metering means associated With said fuel conduit and movableto vary the fuelv supply by the movement'of said main valve.

2.V A carburetor having a mixture passage, a fuel conduit having an orifice, a throttle valve in said passage at the engine side of said orifice and adapted to be opened as a result of suction effects induced at predetermined operating speeds of the engine and adapted to close said passage .at predetermined low speed of the engine, fuel metering means associated with said orice and movable to vary the fuel supply by the movement of said throttle valve, and' vacuum operated means for opening said orifice when said throttle'valve is closed and movable independently of the latter.

3. A carburetor comprising a casing having an intake passageprovided with an air inlet and a fuel inlet, a throttle valve in said passage at the engine side of said inlets and adaptedto close the passage at predetermined speed of the engine, said valve having a lateral passage therein for permitting the flow of fuel and air past the valve when the latterk is closed and including means for closing the fuel inlet when the engine is not operating.-

4. Acarburetor comprising a casing having an intake passage provided with an air inlet and a fuel inlet, a throttle valve movably axially in said passage at the engine side of said inlets andadapted to close the passage at predetermined speed of thel engine, said valve having means for permitting the flow of fuel. and air past the valve when the latter is in position to close said passage, and a vacuum controlled device for closing lthe fuel inlet When the engine is not operating. v

5. A carburetoroomprising a casing having an intake passage `provided With an air inlet and a fuel inlet, a throttle valve movable axially in saidpassage at the engine side of said inlets and adapted to vclose the `pass'ageat predetermined speed of the engine, said valve having means for permitting the flow of fuel and air pastv the valveWhen the latter is in Aposition to close said passage, and a vacuum controlled device carried by said throttle valve for closing the fuel inlet Whenthe engine is not operating. 6. A carburetor comprising a casing having an intake passage provided with an air inlet and a Venturi constriction, a throttle valve cooperating with said venturi, a fuel nozzle, and means movable independently of said throttle valve andV controlled by the operation of the engine for opening said fuel nozzle When the throttle Vvalve is in position to close said passage.

'7. A carburetor comprising a, casing having an intake passage provided with an air outlet and a Venturi constriction, a stream lined throttle valve cooperating with said venturi, a fuel nozzle, and metering means movable independently of sa'iwd throttle valve and controlled by the operation of the engine for opening said fuel nozzle when the vthrottle valve is in position to close said passage.

` 8. Infa carburetona casing comprising an adjustable portion, a Vfuel nozzle carried thereby, a Ametering pin in said nozzle, and manually operated means for adjusting said casing portion and nozzle relative to said metering pin.

9. A carburetor having an intake passage provided With a venturi, a movable plunger located in said venturi and operatedby engine suction to controlthe effective .opening in the passage adjacent said venturi, cushioning means for said plunger located outside said intake passage, means interconnecting said plunger and said cushioning means, a source of fuel supply, metering meansl for the fuel including relatively movable parts, the movable part of the metering means being moved asa resultof the engine suction but said metering means being constructed tocontrol the fuel independently of the engine suction.

10. A carburetor having an intakepassage, a throttle valve adapted to be opened solely by differences in pressure in said passage, a fuel nozzle, a metering device movable With said valve and having means for varying the fuel flow through the nozzle independently of the variations in pressure resulting from the engine operation, Vand means operative to close said Valve but ineffective to open the same.

11. A down-draft carburetor comprising a casinguhaving an inlet passageprovided With an air' inlet anda fuel inlet, a vacuum operated throttle valve in said passage forl controlling the flow'of airfrom said air inlet, and a vacuum operated device having Va Valve for closing said fuel inlet when the engine is not operating.

l2. A carburetor comprising acasing provided with an intake passage having air and fuel inlets and a venturi, arthrottle valve movable axially in the passage Aand cooperating With said venturi to open and substantiallyclose the passage, said valve being at` the engine sideof said inlets and being actuatedby pressure differences at opposite sides thereof,.and mechanism extending exteriorly of the casing. forv closing said valve but ineffective to openA the same.

13. A carburetor comprising a casing provided with an intake passage having. air and fuel inlets and a venturi, a stream-lined throttle valve movable axially in the passage and cooperating with said venturi to open and substantially closeA the passage, said valve being at the engineA side o f said inlets and being actuated by pressure differences at opposite sides thereof, and spring controlled mechanism extending exteriorly of the casing for closing said valve butineffective to open the same.

14. A carburetorrcomprising a casing having an intake passage provided with air Aand fuel inlets and a Venturi constriction at the engine side of said inlets, a throttle valve movable axially substantially within said constriction at the engine side of said inlets and adapted to be opened by differences in pressure vacting thereon, and manually operated means for closing said valve.

l5. A carburetor comprising ,a casing having an intake passage provided with air and fuel inlets and a Venturi constriction at the engine side of said inlets, a throttle valve movable axially substantially Within said constriction at the engine side of said inlets and adapted to be opened by differences in pressure acting thereon, and manually operated means for controlling the position of saidvalve but ineffective to open the same, said valve having means remote from the engine and movable therewith to meter the fuel. 

